FILENAMES: powermatic_30b_repair_7.jpg powermatic_30b_repair_8.jpg powermatic_30b_repair_11.jpg powermatic_30b_repair_12.jpg powermatic_30b_repair_13.jpg powermatic_30b_repair_14.jpg powermatic_30b_repair_15.jpg powermatic_30b_oem.jpg DESCRIPTION: These are pictures of a Powermatic belt and disc sander being restored. Posted by Matt Isserstedt . The following description was provided: ================================================================= Here is the first installment of some repairs I made to my Powermatic #30B belt & disc sanding machine. powermatic_30b_repair_8.jpg This is the original motor mount. It is non-original, a little cobbled, and I finally understood how it worked after complete disassembly in a tight space I could barely fit my hands. I didn’t trust the two sheetmetal tabs acting as a pivot for the motor to hold up for very long. Powermatic’s OE design includes several shaft collars which I think would work just fine. The problem again is access inside the cabinet. It would be next to impossible to tighten a setscrew on a shaft collar, let alone see the bugger and not drop it somewhere inside the cabinet. I opted for a clean-sheet design. powermatic_30b_repair_11.jpg Here is my solution. I liked the idea of a round pivot. I also liked the idea that ONE accessible screw would mount and dis-mount the motor. So I came up with a special shoulder bolt. I threaded a piece of 3/8" O-1 round stock 3/8-16 on the end, and welded a socket head cut off a 1/2-13 bolt to it. Fully tightened it acts as a pivot rod. The rest of the pieces are 3/8" x 1" cold-rolled flat bar plus a piece of 1/4" plate to mount the motor. powermatic_30b_repair_7.jpg Here is the first fitting test of the motor mount. I installed it with two 5/16-18 socket head bolts and it seems to fit just fine. I also tapped the 1/4" plate for 5/16-18 bolts which I actually use as studs in this case. The nuts and washers to mount the motor are impossible to access inside the machine cabinet, so the idea is to bolt the motor to its plate, then install the long socket head pivot/screw to actually mount the motor. More to come on this project as it develops... Matt Isserstedt 20 January 2003 matt.isserstedt@gm.com ------------------------------------------------ Greetings, here are a few shots of what I've been working on lately, a new motor mounting for a Powermatic #30B belt and disc sander (12" disc, 6x48 belt, the "B" denotes integral dust collector). Here is how the motor mounting came to me, two pieces of sheetmetal hinged on two tabs. The thing didn't look right and it was hard as can be to extract from the enclosure. The mounting plate had been doubled up and another sheet welded to it...guess due to some failure in the design. I should start by saying that this is a TIGHT spot. I can barely put my hands inside the sander's housing due to the fact that the 1.5hp motor takes up most of the room! http://www.metalworking.com/dropbox/powermatic_30b_repair_15.jpg Here is what the OEM design looks like from the parts and service manual. I balked immediately when seeing the shaft collars. Again due to the fact that I'd be hunting and fishing and dropping parts where I couldn't see them at all. http://www.metalworking.com/dropbox/powermatic_30b_oem.jpg The other thing I didn't like was that the angle brackets weren't positively aligned at all, just one bolt holding each one in place, with the guide shaft holding it all together. I don't have that many hands. Again, due to the enclosure size, the required procedure is to bolt the motor to its mounting plate OUTSIDE the enclosure, then insert and assemble the mount. Here is my solution: http://www.metalworking.com/dropbox/powermatic_30b_repair_14.jpg A solid structure of 3/8" x 1" flat stock, with a 3/8" pivot shaft and a 1/4" thick mounting plate. The pivot rod is a piece of ground O1 stock, not hardened. It is threaded 3/8"-16 and threads into the last stationary hinge mount...all others are slip-fits. I welded a socket head cut from a 1/2" bolt to the end of the rod, using a thin guiding pin I left on the head. I turned the weld to finish it back to normal diameter. I finished the rounded hinges on the rotary table after bandsawing to rough size. Surface plate/height gage came in handy for laying out holes (I did this instead of jig-drilling with the Bpt to test out my "Optical Center Punch"....more on this device later) Here is the bottom view of the assembly. The motor mounting plate attaches to the surface you see here. http://www.metalworking.com/dropbox/powermatic_30b_repair_13.jpg The "hinges" were initially attached and aligned to the crossbar mount with 10-24 flathead screws, I later TIG welded them solid to prevent any breakage. Here is an assembly view of the mount. http://www.metalworking.com/dropbox/powermatic_30b_repair_12.jpg It works extremely well! Lessons learned for a future design would have been to leave a dog point or P-point guide for the male threaded end of the pivot rod. I went with a Higby end screw thread which is nice, but harder to get lined up than it could be, mainly because I can't see back there and have to "feel" the alignment of the hinges. However, the installation of the motor is very smooth and I will be surprised if I can break it within the next 20 years of use! Matt Isserstedt 02 Feb 2003 matt.isserstedt@gm.com